The roles of prostaglandins and biogenic amines in uterine vascular effects of estrogen will be examined via a multidisciplinary approach. Pharmacologic and biochemical techniques will be utilized to investigate the alpha-adrenergic receptor involvement in the response. Immunohistochemical and autoradiographic techniques will be employed to identify the source and nature of the alpha-adrenergic agonist. On line monitoring of uterine blood flow with doppler probes is being implemented, and will be used to follow response to alpha-adrenergic agonists delivered via cannulae in the uterine arterial supply (Rat). High pressure liquid chromatography with electrochemical detection and radioimmunoassays are being used to quantitate uterine biogenic amines, prostaglandins and prostaglandin metabolites during the response.